Certain aspects of the present disclosure relate to techniques for estimating a channel using soft-windowing. A user equipment (UE) may determine, based on a cyclic prefix (CP) length of a channel, a timing window for sampling reference signals transmitted on the channel, determine a set of weights to apply to samples obtained within the determined timing window, wherein each weight corresponds to a sample obtained within the determined window, and estimate the channel by applying the weights to the samples.

A receiver includes a channel estimation module, a delay spread module, and a smoothing module. The channel estimation module generates a channel estimate for a channel in frequency domain based on a signal received through the channel in time domain. The delay spread module determines a delay spread of the channel in the time domain. The delay spread is an amount of time after which a channel response drops to less than or equal to a predetermined threshold. The smoothing module smooths the channel estimate by applying a filter with unequal taps in the frequency domain. The taps are based on the delay spread. The filter does not attenuate samples of the channel response within the delay spread in the time domain. The filter attenuates noise outside the delay spread of the channel.

Methods and systems are provided for adaptive guard interval (GI) combining. A signal carrying a symbol that is preceded by a guard interval (GI) that includes a portion of the symbol may be received, and a portion of the GI that is free from inter-symbol interference (ISI) may be determined. Only a part of the ISI-free portion of the GI may be selected. The selected part of the ISI-free portion of the GI may be less than a whole of the ISI-free portion. The selection may be configured based on a parameter that is applied to a function used in extracting the symbol. The parameter may be a timing adjustment, relative to a start of the symbol, applied to the function when extracting the symbol. Only the part of the ISI-free portion of the GI may then be extracted and combined with a corresponding portion of the symbol.

A method for estimating angle information for a wireless communication system includes receiving, by a wireless transmit/receive unit (WTRU), a plurality of first training symbols during a first period of time, wherein the plurality of first training symbols is transmitted using a first transmit beamforming vector fixed during the first period of time and received using a first receive beamforming, vector varied during the first period of time; estimating, by the WTRU, a plurality of first channel delay values based on the plurality of first training symbols; estimating, by the WTRU, a plurality of first channel values based on the plurality of first channel delay values; and estimating, by the WTRU, a first angle value of a path of a wireless channel based on the plurality of first channel values.

Methods, systems, and devices for wireless communications are described that provide time synchronization via wireless communications for devices that use strict timing synchronization. A user equipment (UE) may obtain time synchronization via a wireless connection between the UE and a timing source that may be associated with a base station (or another wireless device). In some cases, the timing source may be synchronized at the UE by determining, using periodic synchronization resources, a propagation delay between the UE and the base station that is based on a timing of a line-of-sight instance of a transmission between the base station and the UE. The propagation delay may be used to determine a timing advance value for use in timing synchronization. One or more devices may be coupled with the UE and the UE may provide commands to the one or more devices that are synchronized according to the synchronized timing source.

Provided is a transmission device for transmitting data in a wireless communication based on DFT-spread OFDM. Specifically, provided is a transmission device which outputs a first sub-band and a second sub-band by performing DFT on an input symbol with a tail part and a head part in which at least one 0 has been inserted by a DFT block controlled by a processor, outputs a signal by performing IDFT on the first sub-band which has been mapped by a first IDFT block, allows the signal to be filtered by a first band pass filter, outputs a signal by performing IDFT on the second sub-band which has been mapped by a second IDFT block, and allows the signal to be filtered by a second band pass filter.

A wireless transmit/receive unit (WTRU) may generate a first signal that utilizes a tail suppression signal generated from data and utilizes a first unique word. Elements of the data and the first signal may be mapped to one or more discrete Fourier transform spread (DFT-S) functions. An inverse DFT on symbols generated by the one or more DFT-S functions may be performed to generate a second signal for transmission.

Methods and systems are provided for adaptive guard interval (GI) combining. A signal carrying a symbol that is preceded by a guard interval (GI) that includes a portion of the symbol may be received, and a portion of the GI that is free from inter-symbol interference (ISI) may be determined. Only a part of the ISI-free portion of the GI may be selected. The selected part of the ISI-free portion of the GI may be less than a whole of the ISI-free portion. The selection may be configured based on a parameter that is applied to a function used in extracting the symbol. The parameter may be a timing adjustment, relative to a start of the symbol, applied to the function when extracting the symbol. Only the part of the ISI-free portion of the GI may then be extracted and combined with a corresponding portion of the symbol.

The present invention relates to a method of improving the performance in bandwidth constrained communication systems while reducing the complexity of the equalizer used for information retrieval, as well as to improving the capacity of communication systems. These properties are achieved by appropriate information encoding, prior to signal shaping before transmission, whereas the equalizer complexity is reduced by applying the intersymbol interference shortening filter prior to the information retrieving equalization. A proper combination of the recounted elements is capable of providing a qualitatively improved and previously unsuspected performance, as compared to its constituent elements.

A wireless transmit/receive unit (WTRU) may generate a first signal that utilizes a tail suppression signal generated from data and utilizes a first unique word. Elements of the data and the first signal may be mapped to one or more discrete Fourier transform spread (DFT-S) functions. An inverse DFT on symbols generated by the one or more DFT-S functions may be performed to generate a second signal for transmission.